Three Hundred Sixty Pound Phoenix

After charging magic into the blade of your weapon, you release the magic as you swing causing a spiraling blade of energy to shoot forth. Each creature in a 10ft wide, 60ft line must make a Dexterity saving throw. A creature takes 8 d8 slashing damage and is knocked prone on a failed save, or half as much damage and is not knocked prone on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.